Prevalence of glaucoma in a rural East African population.

PURPOSE: To determine the prevalence of glaucoma in an adult population in rural central Tanzania. METHODS: Six villages were randomly selected from eligible villages in the Kongwa district, and all residents more than 40 years of age were enumerated and invited to a comprehensive eye examination including presenting visual acuity, refraction, automated 40-point Dicon (San Diego, CA) suprathreshold screening field test, Tono-Pen (Bio-Rad, Inc., Boston, MA) intraocular pressure (IOP) measurement, and standardized examination by an ophthalmologist of anterior segment, optic nerve head, and retina after pupil dilation. Gonioscopy and Glaucoma-Scope (Ophthalmic Imaging Systems, Sacramento, CA) optic disc imaging were performed on those with IOP higher than 23 mm Hg and cup-to-disc ratio (c/d) more than 0.6 and on a 20% random sample of participants. RESULTS: Of 3641 eligible persons, 3268 (90%) underwent ophthalmic examination. The prevalence of glaucoma of all types was 4.16% (95% confidence interval [CI] = 3.5, 4.9%). Primary open-angle glaucoma (OAG) was diagnosed in 3.1% (95% CI = 2.5, 3.8%), primary angle-closure glaucoma (ACG) in 0.59% (95% CI = 0.35, 0.91%), and other forms of glaucoma in 0.49%. The prevalence of glaucoma was found to be sensitive to changes in the diagnostic criteria. CONCLUSIONS: The high prevalence of OAG in this group was similar to that of African-derived persons in the United States but less than in African-Caribbean populations. ACG was more prevalent in east Africans than suggested by anecdotal reports.

The epidemiology of infection in trachoma.

Specimens for chlamydial isolation culture and direct fluorescent antibody cytology (DFA) were collected from 1671 women and children from a trachoma-endemic area in Central Tanzania. Trachoma was graded using the new World Health Organization grading scheme, and 54% of the children and 9% of the women had inflammatory trachoma (TF or TI). DFA, using the presence of five elementary bodies as the criterion for a positive test, had a sensitivity of 88.0% and a specificity of 87.5% compared to culture and a sensitivity of 54.7% and specificity of 92.8% compared to clinical diagnosis. Altogether, 52.9% of those with trachoma grade TF were positive on either or both culture and DFA versus 77.0% of those with TI. Twenty-nine isolates were serotyped; 18 were serovar A, ten were serovar B, and one was serovar Ba. Positive cultures or DFA were obtained in 6.9% of those graded clinically as not having TF or TI and in a smaller number of those without any perceptible evidence of disease. Conversely, organisms could not be demonstrated in a number of people with severe inflammation (TI) even though some became positive after multiple repeated culture. These two findings of infection without disease and disease without evidence of infection suggest the importance of the immunologic response to infection in determining the clinical status. DFA was found to be an appropriate test for future field studies of trachoma. Further studies of those with disease but without agent and of those with agent but without disease will help understand the dynamics of infection and transmission and the role of the immune response in this important blinding disease.

Nonocular Chlamydia infection and risk of ocular reinfection after mass treatment in a trachoma hyperendemic area.

PURPOSE: The presence of nasal discharge on a child's face increases the risk of active trachoma, suggesting that Chlamydia trachomatis in nasal secretions may be a possible source of ocular reinfection. The prevalence of chlamydia in nasal secretions and the risk of reinfection after mass treatment was investigated in a hyperendemic area of Tanzania. METHODS: In one village a total of 232 children aged 1 to 7 years were followed before and after mass treatment. Clinical trachoma, and microbiologic evidence of chlamydia, were assessed at baseline, 2 and 4 weeks into mass treatment, and 4 weeks after treatment stopped. The presence of chlamydia in ocular and nasal secretions was determined by polymerase chain reaction-enzyme immunoassay techniques. RESULTS: Of the 232 children, 59% had clinical trachoma and 27% had nasal specimens positive for chlamydia. Children with positive ocular chlamydia specimens and/or clinical trachoma were significantly more likely to have positive nasal specimens. At the end of mass treatment, only 4% of children had positive ocular specimens. However, 1 month after treatment stopped, the incidence of new infection was 21%. The rate of new ocular infections in those who had negative ocular specimens after treatment was similar between those who had positive and those who had negative nasal specimens at baseline. Positive ocular specimens at baseline was not a predictor of risk of new infection after treatment (odds ratio = 1.18, 95% confidence interval = 0.58, 2.40), suggesting these new infections were not the result of latent or persistent organism. CONCLUSIONS: These data do not support a role for nasal secretions in causing reinfection after treatment. One mass topical treatment alone is unlikely to be effective in trachoma hyperendemic areas as shown by the rapid re-emergence of infection.

The epidemiology of trachoma in central Tanzania.

Trachoma is the leading infectious cause of blindness worldwide and data are needed on the epidemiological characteristics of active and residual disease in hyperendemic areas. This study describes the epidemiological characteristics of trachoma in Central Tanzania. Active, inflammatory disease peaks in pre-school children, with 60% showing signs of trachoma. Evidence of past infection, scarring, trichiasis, and corneal opacity, rose with age. In this population, 8% of those over age 55 had trichiasis/entropion. Females of all ages had more trachoma than males, with a fourfold increased risk of trichiasis observed in females. Women who were taking care of children appeared to have more active disease than non-caretakers. Clear evidence of clustering of trachoma by village, and within village, by neighbourhood was found. Clustering persisted even after accounting for differences in distance to water, local religion, and proportion of children with unclean faces. These findings have important implications for a trachoma control strategy.

Risk factors for trichiasis in women in Kongwa, Tanzania: a case-control study.

Women are at a greater risk compared to men for blinding complications from trachoma. In order to evaluate risk factors in women, 205 cases of trichiasis (TT) were selected from 11 villages in rural Tanzania. Each case of trichiasis was matched to two women of the same age and from the same village, who had no clinical signs of trachoma. Factors associated with trichiasis in a conditional logistic regression included history of trichiasis in the women's mother (odds ratio [OR] = 3.6; 95% confidence interval [CI]: 2.0-6.5); sleeping in a room with a cooking fire during childbearing years (OR = 1.8; 95% CI: 1.2-2.8); a home of wood and earth during childbearing years (OR = 2.1; 95% CI: 1.3-3.3); no adult education classes (OR = 2.2; 95% CI: 1.4-3.4); and five or more deaths among her children (OR = 2.6; 95% CI: 1.3-5.1). Detailed measures of prolonged exposure to child care as a young girl and as a mother showed no significant difference between cases and controls. Results from this study characterize women at high risk for severe disease and eventual blindness in a trachoma endemic area.

PIP: Ophthalmologists analyzed data on 205 women with ingrowing eyelashes caused by trachomatous scarring (trichiasis) with data on 410 age- and village-matched controls to determine risk factors for trichiasis in trachoma hyperendemic areas where women face a greater risk of trichiasis than do men. All women lived in the Kongwa subdistrict of Dodoma Region, Tanzania. Cases were 3.6 times more likely to have a mother who also had trichiasis. Family history of fathers or other relatives was not associated with trichiasis, however. Cases tended to have never married (odds ratio [OR] = 3.7), suggesting that in a society that expects marriage women with trichiasis were socially and economically marginalized. Mothers with trichiasis were more apt to experience at least 5 deaths of children than controls (OR = 2.6). The researchers assumed that a factor common to both trichiasis and increased child deaths (e.g., socioeconomic status) accounted for this association. Controls were more likely to have attended adult education classes than cases (OR = 2.2), yet attendance at primary school was not a predictor for trichiasis. Women who had slept in a room with a cooking fire during their reproductive years were more prone to trichiasis than women who did during childhood or as current practice (OR -1.8), indicating a more profound pathogenic response (scarring) to infection with Chlamydia trachomatis during pregnancy. Living in a wood/earth (i.e., traditional) home during childbearing years was also a significant predictor of trichiasis (OR = 2.1). These findings suggest that improving living conditions, educational opportunities, and socioeconomic status during the childbearing years would reduce the risk for trichiasis and blindness.

Examination methods for glaucoma prevalence surveys.

OBJECTIVE: To perform a pilot evaluation of new examination methods for the detection of glaucoma and other causes of visual impairment in rural East Africa. DESIGN: Testing was performed by local eye nurses after a brief training course. Two novel tests of visual function were used, a scotopic sensitivity test and a visual field test performed on a laptop computer. The optic disc was examined with direct ophthalmoscopy after pupillary dilation and compared with standard photographs on a laminated card. Intraocular pressure was measured with a hand-held, electronic tonometer. SETTING: Rural Tanzania. PARTICIPANTS: One hundred twenty adult villagers. RESULTS: The visual function tests could be performed on more than 90% of subjects, and the results were correlated with the size of the optic disc cup, an objective measure of glaucoma injury. CONCLUSIONS: This survey shows the practicality of instrument-based testing of visual function under field conditions.

Hygiene factors and increased risk of trachoma in central Tanzania.

Trachoma remains the major infectious cause of blindness in many developing areas, especially where hygiene is poor. The practices and behaviors associated with an increased risk of trachoma were studied in central Tanzania, where a stratified random cluster sample of 8409 people was examined. Data were collected on family and individual characteristics and behaviors and on trachoma status. Overall, 60% of the children aged 1 to 7 years had active inflammatory trachoma, and 10% of those aged 60 years or older had trichiasis. Regression analysis showed that active inflammatory trachoma in children was associated with the characteristics of the more traditional families and several measures of poor personal hygiene. Two important risk factors for severe inflammatory trachoma were poor facial cleanliness in children (odds ratio of 1.7 [1.17, 2.50]) and household fly density (odds ratio of 1.63 [1.17, 2.29]). Both factors are potentially amenable to intervention. These data suggest that an intervention strategy aimed at these hygiene measures would provide an effective method of controlling trachoma in this region, and a similar approach may be useful in other areas.

Testing a participatory strategy to change hygiene behaviour: face washing in central Tanzania.

A participatory strategy to increase face washing was designed and tested in central Tanzania. Changing children's face-washing behaviour is postulated to be important in preventing the transmission of eye disease, particularly blinding trachoma. The strategy used non-formal adult education techniques at neighbourhood level meetings to build a community consensus to keep children's faces clean for the prevention of eye disease. Men, women, schoolchildren, traditional healers and village social groups participated in the intervention. The strategy was evaluated by observing changes in numbers of clean faces of a sample of preschool children in the village. Clean faces increased from 9% to 33% over the course of a year. Factors which were related to sustained change in children's clean faces included distance to water, age of the child, and presence of a corrugated metal roof. Owning cattle was associated with lack of sustainable change in this population.

Predicting surgical compliance in a cohort of women with trichiasis.

Trichiasis/Entropion are the severe consequences of chronic trachoma during early life. Blindness and vision loss is preventable with timely lid surgery to correct trichiasis. In a trachoma hyperendemic region of Central Tanzania, a two year follow-up survey was conducted among 205 women with trichiasis to determine the proportion who had had surgery and the barriers to having surgery. Only 18% of the women had undergone surgery by the 2 year follow-up. Those who had surgery tended to report more eye problems at baseline and have more corneal opacities at baseline. Barriers preventing women from going to surgery were costs, problem of children left at home alone, and difficulties in identifying someone to accompany them to the health center. Over 2/3 of those who had surgery reported a significant decrease in pain, improvement of vision, and improved ability to carry out activities of daily life. Ways to improve compliance with recommendations for trichiasis surgery need to be developed.

Exposure to children and risk of active trachoma in Tanzanian women.

The authors surveyed the trachoma status of 515 women aged 18-60 years and 527 children aged 1-7 years in the trachoma hyperendemic region of Kongwa, Tanzania, in 1989 to further describe the importance of exposure to young children as a risk factor for active trachoma in women. The women were identified as caretakers, who currently cared for children aged 1-7 years; noncaretakers, who lived with, but did not care for, children aged 1-7; or those without children aged 1-7 in the household. The age-adjusted odds ratios for active trachoma seemed to rise with greater exposure to young children, from 1.00 for women without such children, to 1.63 for noncaretakers and 2.43 for caretakers (trend test, p = 0.08). Among those who lived in households with young children, the prevalence of active trachoma in women increased with the total number of young children cared for and with the number of infected children cared for. The prevalence of active trachoma was 40% (6 of 15) for caretakers of three or more infected children, compared with 0 (0 of 88) for caretakers with no infected children (p < 0.0001). Caring for infected children also appeared to be associated with signs of chronic trachoma in caretakers. Noncaretakers who lived with infected children were not at a significantly increased risk for trachoma compared with noncaretakers who were not exposed to such children (5.4% (three of 56) vs. 5.6% (one of 18); p > 0.4). None of the facial signs observed in the children (flies on the face, nasal discharge, etc.) appeared to increase the odds ratio of active trachoma in caretakers beyond the increase associated with trachoma alone in the child. These data support the hypothesis that active disease in women is associated with direct caretaking of young children with active disease. Strategies that interrupt household transmission may affect the binding sequelae of trachoma in women.

Water availability and trachoma.

As part of an epidemiological survey of risk factors for trachoma in 20 villages in the United Republic of Tanzania, we investigated the relationship of village water pumps, distance to water source, and quantity of household water to the risk of inflammatory trachoma. We also evaluated whether there was an association between the cleanliness of children's faces and these water variables. No association was found between the presence of a village water supply and the prevalence of trachoma. However, the risk of trachoma in the household increased with the distance to a water source--although there was no association with the estimated daily amount of water brought into the house. Likewise, children were more likely to have unclean faces if they lived more than 30 minutes from a water source, but whether they had clean faces was not associated with the daily quantity of water brought into the household. The effect of the distance to water supply on trachoma may well reflect the value placed on water within the family, and this determines the priority for its use for hygiene purposes. The results of the study suggest that changing the access to water per se may be insufficient to alter the prevalence of trachoma without also a concomitant effort to change the perception of how water should be utilized in the home.

Impact of face-washing on trachoma in Kongwa, Tanzania.

Observational studies have suggested that the prevalence of trachoma is lower in children with clean faces than in those with ocular or nasal discharge or flies on the face. We carried out a community-based randomised trial in three pairs of villages to assess the impact on trachoma of a face-washing intervention programme following a mass topical antibiotic treatment campaign. Six villages in Kongwa, Tanzania, were randomly assigned mass treatment plus the face-washing programme or treatment only. 1417 children aged 1-7 years in these villages were randomly selected and followed up for trachoma status and observations of facial cleanliness at baseline and 2, 6, and 12 months. At 12 months, children in the intervention villages were 60% more likely to have had clean faces at two or more follow-up visits than children in the control villages. The odds of having severe trachoma in the intervention villages were 0.62 (95% Cl 0.40-0.97) compared with control villages. A clean face at two or more follow-up visits was protective for any trachoma (odds ratio 0.58 [0.47-0.72]) and severe trachoma (0.35 [0.21-0.59]). This community-based participatory approach to face-washing intervention had variable penetration rates in the villages and was labour intensive. However, we found that, combined with topical treatment, community-based strategies for improving hygiene in children in trachoma-endemic villages can reduce the prevalence of trachoma.

Risk factors for constant, severe trachoma among preschool children in Kongwa, Tanzania.

Trachoma, an ocular infection caused by Chlamydia trachomatis, is the second leading cause of blindness worldwide. The blinding sequelae, which occur in middle age, are felt to be the result of numerous or lengthy episodes of severe inflammatory trachoma in childhood. Risk factors for constant, severe trachoma were identified in a group of children enrolled in a longitudinal study in Kongwa, Tanzania, where villages were randomized in a clinical trial of mass treatment and a behavior modification campaign. In 1989, each of 1,417 randomly selected children had photographs taken of an upper eyelid for determination of their trachoma status. The photographs were graded by a reader who was masked as to the village and date of each photograph. Risk factor data on the family's socioeconomic status, distance to water, and hygiene practices were obtained at baseline. Follow-up examinations occurred 2, 6, and 12 months from baseline. Data from all four time points were available for 82% of the children enrolled. Overall, 10% of the children had constant, severe trachoma, defined as severe trachoma at three or four examinations. The odds ratio for severe trachoma was 1.9 for female children (95% confidence interval 1.3-2.7). Familial cattle ownership and having one or more siblings with trachoma at baseline were also significantly related to the odds of having severe trachoma. Children with a sustainably clean face had lower odds (odds ratio = 0.4, 95% confidence interval 0.3-0.7). A subgroup of 10% of children in these hyperendemic communities always seemed to have severe trachoma, despite enrollment in a mass treatment campaign. Improved face-washing plus antibiotic treatment may decrease the likelihood that these children will be at risk for blinding complications in adulthood.

PIP: Risk factors for constant, severe trachoma were identified in a group of children enrolled in a longitudinal study in Kongwa, Tanzania, where villages were randomized in a clinical trial of mass treatment and a behavior modification campaign. In 1989, each of 1417 randomly selected children had photographs taken of an upper eyelid for determination of their trachoma status. The photographs were graded by a reader who was masked as to the village and date of each photograph. Risk factor data on the family's socioeconomic status, distance to water, and hygiene practices were obtained at baseline. Follow-up examinations occurred 2, 6, and 12 months from baseline. Data from all 4 time points were available for 82% of the children enrolled. 31% of the children in these villages had severe trachoma at baseline. By 1 year follow-up, 22% of the children had severe trachoma despite the mass treatment given 10 months earlier. Overall, 10% of the children had constant, severe trachoma, defined as severe trachoma at 3 or 4 examinations. At every time point, females generally tended to have more severe trachoma than males. The odds ratio for severe trachoma was 1.9 for female children. The prevalence rates varied from 0 in 2 neighborhoods to greater than 15% in 5 neighborhoods. The prevalence rate of constant, severe trachoma in the intervention villages was 8% compared with 12% in the control villages. Familial cattle ownership, having 1 or more siblings with trachoma at baseline, and being female were also significantly related to the odds of having severe trachoma. Children with a clean face had lower odds. They also had a prevalence rate of 4% for constant, severe trachoma compared to 13% in children whose face was not clean. Improved face-washing plus antibiotic treatment may decrease the likelihood that these children will be at risk for blinding complications in adulthood.